Q: My car starts but will not stay running at idle.

asked by on December 02, 2016

My car turns on with no problem now. I had a bad alternator and battery. Before, I would need a jump every time then eventually it just would not start. That problem is now gone but one very annoying one exist. Once it starts, as long as my foot is on the gas, it stays running. The second my foot is taken off, it turns right back off.

My car has 20000 miles.
My car has an automatic transmission.

You may have a dirty or failing idle air control valve. The idle air control valve reads the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle. Since this valve is controlled by the vehicle’s computer, it will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed with the help of the idle air control valve. When the engine RPM drops below the normal range of about ~800 RPM, this often times will cause the engine to stall indicating a dirty or faulty idle air control valve. I would recommend having an expert from YourMechanic come to your location to diagnose and repair your idle air control valve.

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